Download Endocrine PP - Laura Banks

Endocrine
system
Unit 9
• What are the 8 glands of the endocrine system?
• Think back a few chapters, what is translation and
transcription?
Activator: 2.9.2016
• Regulates reproduction, growth and development,
defenses, balance of nutrients in the blood, metabolism,
and energy use
• 0.5 pounds of endocrine tissue
Role of endocrine system
• Chemical messengers
• Hormone means “to arouse” by altering cellular activity
What are hormones?
• Start by circulating in the blood
• Hormones bind to certain cells or organs
Mechanisms of hormones
action
• Target Cell/Organ- The cell or organ a hormone attaches
to
• In order for the target to respond to the hormone, a
protein receptor must be present on the plasma membrane
or in the cell
Hormone attachment
• Activation means the hormone causes a change in the
target cell
2 types of hormone activation:
1. Steroids (cholesterol and sex hormones) are lipid
soluble
2. Amino-acid based (proteins, peptides, and amines) are
non-lipid soluble
Hormone activation
• Lipid-soluble, so they can move through the plasma
membrane
1. Steroidal hormone
activation
• Hormone diffuses through plasma membrane
Step 1
• Hormone binds to specific receptor protein
• Becomes a hormone-receptor complex (HRC)
• HRC enters the nucleus
• Hormone (H) + Receptor Complex (RC) = HRC
Step 2
• The HRC binds to DNA
Step 3
• Certain genes in the DNA are altered, new mRNA is
transcribed
• Think back to translation and transcription
Step 4
• mRNA is translated, new protein is created
• This protein will cause the desired effect to the cell
Step 5
• Non lipid soluble, so the hormones must attach to the
plasma membrane directly
Amino-acid hormone
activation:
• Hormone binds to membrane receptor attached to
membrane
Step 1
• Binding sets off a series of reactions that activates
enzymes w/in the cell
Step 2
• The enzyme then catalyzes (speeds up) a reaction that
produces a messenger molecule
Step 3
• Messenger molecule creates the change desired within the
cell
Step 4
1.
2.
3.
4.
5.
Diffuse thru PM
H + R = HRC, enters nucleus
Bind to DNA
Alter genes of DNA & makes new mRNA
Make a new protein
STEROIDAL
1.
2.
3.
4.
Attach to receptor in PM
Enzymes are released
Speed up the production of a messenger molecule
Messenger molecule creates the desired effect on cell
NON- STERIODAL
How do glands know
when to release
hormones?
• Use negative feedback mechanisms to maintain hormone
levels in the blood
How do glands know
when to release
hormones?
• Too much of a hormone, the glands stop producing
• Too little, and the glands produce more
What are negative
feedback mechanisms?
•
•
•
•
3 main categories of stimuli:
Hormonal
Humoral
Neural
What kinds of stimuli
activate endocrine
glands?
• Endocrine organs are prodded by other hormones to
create their own hormones
• rhythmic/always working
Hormonal stimuli
• Step 1: Hypothalamus secretes hormones that activate
pituitary gland to release hormones.
Example of hormonal
stimuli
• Step 2: Pituitary gland releases hormones that activates
adrenal glands AS WELL AS cut off the hormones of the
hypothalamus
• Step 3: New hormones are released by the adrenal
glands into the body AS WELL AS cutting off the
hormone production in the pituitary glands
• This allows the hypothalamus to start producing
hormones again
• Initiated by low levels of ions or nutrients monitored by
endocrine organs
• Works in short bursts/ Used only when needed
Humoral stimuli
• Hormones respond to neural activity
• Ex) responding to stress
• Sympathetic nervous system produces norepinephrine
which when stressed, which causes increased heart rate,
blood pressure, etc.
Neural stimuli
Endocrine organs
• “Master gland”
• Hangs by a stalk under the hypothalamus
2 parts:
1. Anterior
2. Posterior
Pituitary Gland
• 6 total hormones produced here.
• 2 work on non-endocrine targets
• 4 work on other endocrine glands, these are called
trophic hormones
Anterior pituitary
1. Growth hormone (GH)- division of cells, growth of
bones and muscle
2. Prolactin (PRL) - Milk production of the breasts
2 Non-endocrine targets
The 4 tropic hormones stimulate:
• Follicle-stimulating (FSH)- Helps regulates menstrual
cycle and egg production in women, sperm production in
men
• Luteinizing (LH)• Thyroid-stimulating (TSH)- stimulates the thyroid to
release its hormones
• Adrenocorticotrophic (ACTH)- stimulates the adrenal
glands to release their hormones
4 endocrine gland targets
• Works directly with the hypothalamus to secrete the
hormones produced by the hypothalamus
Posterior pituitary
•
•
1. Oxytocin (OT) :common in women, stimulates
contractions during labor, sex, and also causes milk
ejection
2. Antidiuretic hormone (ADH) Kidneys reduce
water excretion (inhibits urine production)
2 hormones from
posterior pituitary
Large gland made up of two bulbs on each side of the
trachea
1. Thyroid hormone
2. Calcitonin
Thyroid gland
• Major metabolic hormone- Controls the rate at which
glucose is converted into energy and heat
• Also controls normal tissue growth and development
Thyroid Hormone
• Decreases calcium levels in the blood by depositing
calcium in the bones
• Only secreted when calcium levels are high
Calcitonin
• Tiny masses of tissue found on the posterior surface of
the thyroid gland
Parathyroid glands (4)
• Releases osteoclasts
• Opposite role of calcitonin
Effect of PTH
• Curve over the top of the kidneys
1. Adrenal cortex
2. Adrenal medulla
Adrenal glands
•
•
•
•
3 types:
Mineralocorticoids
Glucocorticoids
Sex hormones
Hormones of the adrenal
cortex
• Regulate mineral (or salt) & water balance in the blood
Mineralocorticoids
• Increase blood glucose levels
• Inhibit some pain-causing molecules (anti-inflammatory)
Glucocorticoids
• Both produced in small amounts throughout life
regardless of gender
i.
ii.
Androgens (male sex hormone)
Estrogens (female sex hormone)
Sex hormones
1. Epinephrine
2. Norepinephrine
• Produced by stimulating SNS
Hormones of the adrenal
medulla
• AKA adrenaline and noradrenaline
• Increase blood glucose and rate of metabolism
• Spark the “fight or flight” response
Epinephrine and
norepinephrine
• The pancreas houses tiny little endocrine glands called
the pancreatic islets
1. Insulin
2. Glucagon
Pancreas
• Both regulate the amount of sugar in the blood, but in
opposite ways
Roles of insulin and
glucagon
• Small gland located in the brain
Pineal gland
• Effects how tired we are
• Levels rise and fall throughout the day:
• High levels = drowsy
• Levels are lowest around noon
Melatonin
• Located in the upper thorax, posterior to the sternum
• Produces thymosin
Thymus gland
• Highly useful in immunity and defenses of the body
• Stimulates the production of disease fighting T-cells
• Only active until you hit puberty – slowly shrinks and is
replaced by fat
Thymosin
• Grouped by male and female organs
• Female gland: ovaries
• Male gland: testes
Gonads
• Produce sex cells (ova, or eggs)
• Also produce 2 hormones:
1. Estrogen
2. Progesterone
Ovaries
• Estrogen stimulates development of the female
reproductive organs
• Progesterone acts with estrogen to bring about and
regulate the menstrual cycle
Hormones of the ovaries
• Produce sex cells (sperm)
• Also produce androgens (testosterone is the most
common)
Testes
• Androgens stimulate:
1. Development of the male reproductive organs
2. Secondary sex characteristics
3. Increases sex drive
Hormones of the testes
• The placenta is a temporary organ formed during
pregnancy, found in the uterus
developmental gland: the
placenta
• Helps to increase levels of estrogen and progesterone in
the mother
• This improves the lining of the uterus, further
development of breasts, and lactation
What does the placenta
do?